Module 2: Figure NO and cyclic GMP signalling



Nitric oxide (NO) and cyclic GMP (cGMP) signalling pathways.

The nitric oxide (NO) signal can either diffuse in from other cells as a paracrine signal or it can be generated within the cell by different NO synthases (NOSs). The NO has two main actions. It can stimulate soluble guanylyl cyclase (sGC) to form the messenger cyclic GMP (cGMP), which can act through cyclic nucleotide-gated channels (CNGCs) to promote Ca2+ entry or it can activate cyclic GMP-dependent protein kinase (cGK). Cyclic GMP is also formed by a plasma membrane guanylyl cyclase (pGC), which is part of the single membrane-spanning receptor activated by a variety of peptides such as atrial natriuretic peptide (ANP), brain type natriuretic factor (BNP), C-type natriuretic factor (CNP) and guanylin. The other main action is through reactive nitrogen species (RNS) signalling mechanisms that depend upon an S-nitrosylation reaction, which is reversed by denitrosylation reactions.